Friction-clutch-driving mechanism



Dec. 30, 1930. K. MAIER v 1, 5,

' FRICTION CLUTCH DRIVING MECHANICS! Fi ledSept. 2.-19 2'1 Patented Dec.35%, 1%3 3 KARL MAIER, OF STUT'IGART GERMANY, ASSIGNOB TOUNION SPECIALMASCHINEN- FABBIK G. M. B. I-I., OF STUTTGART, GERMANYFRICTION-CLUTCH-DRIVING MECHANISM Application fil ed, September 2, 1927,Serial No.

The present invention relates to friction driving mechanism,iarti'cularly suitablefor sewing machines. I

Friction drives have already been used for 5 driving sewing machines inwhich the friction d of the clutch is coupled with a pulley for thesewing machine drive by actuating a rocking lever by means of a footpedal. In

such known drivesof this type however the 10 seamstress has to maintainthe clutch permanently in engagement during the sewing operation so thatthe friction effect is maintained solely by constant foot pressure.

Such drives are for the most part provided with abrake shoe for thepulley driven by the friction disc which, on the one hand is underspring action and on the other hand is lifted during the stitchingprocess from the driven pulley and must be maintained in this positionagainst the spring action mentioned.

As not only the engagement of thefriction clutch, but also the liftin gof the brake shoe is effected by the foot lever it follows that theseamstress must not only maintain the friction effect by footpressurebut also retain the brake shoe in its inoperative po. -tion by footpressure.

Fr short intermittent sewing operations it may not be inconventient tooperate the two devices by foot pressure, but it is obvious that whenworking for a considerable time with the foot constantly in action theseamstress becomes tired and the foot is also 7 tired in sympathy.

The objectof the invention is to reduce the foot pressure necessary foroperating the friction clutch. and to dispense with it altogether or asfar as possible during the sewing operation.

i iccording to the present invention after the rocking lever or doublearm has been depressed by means of a foot lever thereby engaging thefriction clutch the latter is held in the position of friction bysuit-able means without maintenance of the foot pressure. A link mayadvantageously be used as the means aforementioned which on actuatingthe rocking lever is completely or substantially completely extended.

217,222, an d in Germany September 11, 1926.

As a result of this it is possible to construct the rocking lever as adouble lever, one lever arm of which is connected with the link which inturn connected with an engaging arm. In order to be able to adjust theextended position of the link a set screw is provided on the rockinglever or double arm lever. Finally the engaging arm has two portions atan angle to each other, one having a bifurcated e d to which is fittedthe link drive for a sewing machine provided with the improvement,whilst Figure 2 is a similar view in a different position of theelements, a portion of the device being removed for the purpose ofclearness.

Thesewing plate a; has a bearing plate 7) in the bearing hole 0 of whichismounted an axle d which in turn carries the mounting e. The latter isprovided with a bearin f for an axle g, which, on the one hand isadapted toreceive thebelt pulley h with the friction disce', and. on theother hand the belt pulley 1b which is connected by means of a belt withthedriving wheel of the sewing machine.

The bifurcated ends a of an engaging arm m pivotally mounted at Z grip adriver 0 which is connectedwith the boss of the belt pulley it so thaton a rocking movement of the engaging arm on the driver 0, belt pulley hand friction disc 2' are displaced to the righton the axle g and thefriction disc 2' is coupled with the belt pulley 7a to be driven.

The engaging lever an is however according to the example,shown,constructed as a double armed lever m, p, the element m carrying alink r pivotally. mounted at g which is articulated at s with the arm tof a double rocking lever t, o, pivotally mounted at u whilst the otherelement p of theengaging lever carries a brake shoew which bears againstthe belt pulley is and retains this in the position of rest.

The rocking lever o is connected by means of a rod 00 or chain with afoot lever, which is not shown, operated by the seamstress. A

spring y attached to the bracket for the bearclutch and cause the brakeshoe w to engage the belt wheel. The spring y is connected to thisbracket and to the lever v and this spring normally tends to lift theleft hand end of the lever u when the trea'dle is released. -This alsotends to buckle the toggle connectionfor peri itting t.ie belt wheel tobe released and stopped. V

The apparatus is operated as follows The belt pulley h and friction ring2' run continuously. As soon as any stitching is to be effected theseamstress depresses the foot lever, the rod :0 moves in the directionof the arrow (Fi ure 1) so that the rocking lever e, t, is swung aboutits mounting a. T he link 1" is entrained in this movement so thattheelement t of the lever and the link 1 come into an extended or nearlyextended position as shown in Figure 2. This action results in theengaging arm constructed as a double armed lever on, p, swinging aboutits mounting Z thereby on the one hand raising the brake shoe w from thebelt pulley 7c and on the other hand displacing the bifurcated ends n ofengaging arm m, the driver 0, belt pulley hand friction disc 2' andaccordingly engaging the friction clutch so that the belt pulley 7c isnow driven.

The effect of thelink r being brought into wholly or nearly whollyextended position is on the one hand the tensioning of the spring 1 andalso a tensioning 0f the spring 3/; The link 0 when in alignment withthe lever t, 4; holds the lever with the brake released and the frictionclutch in engagement so that the machine is operated. This takes all theload off from the operator. When the treadle is released the spring :z/will lift the left hand end of the lever t, '0, thus buckling the toggleand the combined action of the spring 3 and the spring 3/ will cause thebrake to be applied and hold the brake applied, thus releasing theoperator from the 7 strain of holding the parts in position forrendering the machine idle.

Finally, it is also provided that the extended position of the link 0"is fixed, this being effected by means of a set screw 2 which alsoallows of adjustment of the extended position of the link r so that thepoint of articulation s can be displaced.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is A friction clutch driving mechanism including incombination an element to be driven, a' driving member movable intofrictional engagement therewith, an engaging lever having connectionwith said driving gage the driving member from the driven member, arocking lever, a link interposed between said rocking lever and saidengaging lever, said link and rocking lever being movable into alignmentwhen the driving member is in engagement with the driven member forholding said members in engagement, a stop for limiting the movement ofsaid rocking lever when said link and lever are in alignment, a springfor moving said rocking lever to throw the link and lever out ofalignment, and a manually operated device connected to said rockinglever for moving the same to bring the link and lever into ali nment andthe driving member into clutching engagement with said driven member.

In testimony whereof, I afhx my signature.

KARL MAIER.

